A flux feeding apparatus and flux optimization selection method

ABSTRACT

A flux feeding apparatus 10 for delivering flux to a mold 13 during a continuous casting process is described. The apparatus comprises: a plurality of silos 20a-20c each containing a different flux or flux component; a receiver 52 for receiving process parameters of the casting process; and a controller 44 which is configured to: analyse the process parameters received by the receiver 52; determine whether a current flux composition is appropriate for the received process parameters; and if the current flux composition is not appropriate for the received process parameters, change the delivery of flux or flux components from the plurality of silos to provide a required flux composition to the mold 13 for the received parameters. A corresponding method is also described.

TECHNICAL FIELD

The present disclosure relates to a flux feeding apparatus and methodfor delivering flux to a mold during a continuous casting process.

BACKGROUND OF THE INVENTION

It is customary to apply a mold flux, which may be a powder or granularmaterial, onto the top of a slab during continuous casting of a moltenmetal, such as steel. The flux turns into slag when sufficiently heatedby the molten metal. Fluxes are engineered synthetic slags formed bycompounds containing oxides, minerals and carbonaceous materials whichare selected to provide desired characteristics. For example, the fluxmay include silica, bauxite, calcium silicate/wollastonite, feldspar,soda ash, fluorospar, lithium carbonate, etc.

At the zone of contact with the liquid metal, the flux serves to preventreoxidation and avoid heat loss so as to prevent prematuresolidification of the liquid metal. The flux also absorbs non-metallicinclusions at the liquid slag-metal interface, thereby producing cleanermetal. Further, at the zone of contact with the solidified metal, theflux provides lubrication between the solidified metal shell and themold. The flux also plays an important role in controlling heattransfer, particularly in a horizontal direction. These functions have adirect impact on the quality and operational stability of the caststeel. For example, inadequate lubrication of the flux can cause loss ofcontainment of the liquid steel due to high friction and shell tearing.Insufficient heat removal will result in thin shell that cannotwithstand the ferrostatic pressure and lose steel containment. Excessiveheat removal can cause cracks to form on the steel surface, etc.

Flux feeding apparatuses are known which deliver flux automatically orsemi-automatically to the mold. For example, in US 2013/0081777, loadcell weight sensors are used to control the rate of addition of flux tothe mold.

The present invention seeks to provide an improved flux feedingapparatus and method.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a fluxfeeding apparatus for delivering flux to a mold during a continuouscasting process, the apparatus comprising: a plurality of silos eachcontaining a different flux or flux component; a receiver for receivingprocess parameters of the casting process; and a controller which isconfigured to: analyse the process parameters received by the receiver;determine whether a current flux composition is appropriate (e.g.optimized) for the received process parameters; and if the current fluxcomposition is not appropriate for the received process parameters,change the delivery of flux or flux components from the plurality ofsilos to provide a required flux composition to the mold for thereceived process parameters.

According to another aspect, the process parameters may includeuser-input parameters and sensed parameters.

According to another aspect, the process parameters may include one ormore of: the grade of metal being cast, casting rate/speed, fluxconsumption rate, heat transfer rate, slag temperature, metaltemperature, slag thickness, width, section size, taper.

In another aspect, the controller may select one or more of theplurality of the silos so as to form a mixture of the individual fluxesor flux components.

In yet another aspect, the controller may select one of the silos so asto deliver the flux contained therein to the mold.

In another aspect, the flux feeding apparatus may further comprise afeed head which is connected or connectable to the plurality of silos,wherein the controller is configured to supply the feed head with fluxor flux components from one or more of the plurality of silos so as todeliver the required flux composition to the mold.

In another aspect, the feed head may be connected to the silos via amanifold and one or more valves which selectively couple the silos tothe feed head.

In another aspect, the one or more valves may be metering valves.

In another aspect, one or more mixing devices may be provided to mix theflux or flux components prior to or in the feed head.

In yet another aspect, the flux feeding apparatus may further comprisean intermediate hopper and a transfer apparatus for transferring moldflux from the silos to the intermediate hopper, wherein the feed head isconnected to a feed hopper which is configured to receive flux from theintermediate hopper.

In another aspect, the transfer apparatus may include a vacuum fortransferring flux from the silos to the intermediate hopper, and whereinthe controller is further configured to control the operation of thevacuum.

In another aspect the transfer apparatus may further comprise a valvewhich is operable between a first closed position which prevents moldflux from transferring to the intermediate hopper when the vacuum is on,and a second open position which allows mold flux to transfer to theintermediate hopper when the vacuum is off.

In another aspect, the valve may be a flapper valve having a counterweight.

In another aspect, the flux feeding apparatus may further comprise aventuri pump to supply the flux to the feed head.

In another aspect, if the current flux composition is not appropriatefor the received process parameters, the controller may generate analert for an operator.

In another aspect, in response to the alert, the operator may instructthe controller to change the delivery of flux or flux components fromthe plurality of silos to provide a required flux composition to themold for the received process parameters.

In another aspect, the flux feeding apparatus may further comprise oneor more sensors for determining the process parameters, the one or moresensors being connected to the receiver.

According to another aspect of the invention, there is provided a methodfor delivering flux to a mold during a continuous casting process, themethod comprising: receiving process parameters of the casting processat a controller; analysing the process parameters using the controller;determining whether a current flux composition delivered to the moldfrom a plurality of silos each containing a different flux or fluxcomponent is appropriate for the received process parameters; and if thecurrent flux composition is not appropriate for the received processparameters, changing the delivery of flux or flux components from theplurality of silos so as to provide a required flux composition to themold for the received process parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearlyhow it may be carried into effect, reference will now be made, by way ofexample, to the accompanying drawings, in which:

FIG. 1 is a front view of a flux feeding apparatus;

FIG. 2 is a rear perspective view of the apparatus of FIG. 1; and

FIG. 3 is a schematic view of a silo section of the flux feedingapparatus.

DETAILED DESCRIPTION

It is to be understood that at least some of the figures anddescriptions of the invention have been simplified to illustrateelements that are relevant for a clear understanding of the invention,while eliminating, for purposes of clarity, other elements that those ofordinary skill in the art will appreciate may also comprise a portion ofthe invention. However, because such elements are well known in the art,and because they do not facilitate a better understanding of theinvention, a description of such elements is not provided herein.

FIG. 1 illustrates an exemplary flux feeding apparatus 10 for deliveringflux to a mold 13 during a continuous casting process.

In one embodiment the flux feeding apparatus 10 can include four majorcomponents: a transfer apparatus 12; an intermediate hopper 14, acontrol apparatus 16, and a delivery apparatus 18. The transferapparatus 12 transfers flux in powder or granular form from a silo 20 tothe intermediate hopper 14. The silo 20 may include, for example, one ormore large bags or barrels or other containment structures suitable forcontaining flux or flux components. The delivery apparatus 18 feeds flux11 from the intermediate hopper 14 onto molten metal 15, such as steel,within the mold 13.

In one embodiment, the transfer apparatus 12 can include a vacuum hopper(or vacuum receiver) 22 having an inlet port 24 to which one end 26 ofeach of a plurality of flexible suction tubes 28 are connected. Theother ends 30 of each of the plurality of flexible suction tube 28extend into the plurality of silos 20 such that each silo is accessed byat least one flexible suction tube.

In one embodiment vacuum hopper 22 also includes an outlet at the bottomfor transferring mold flux to the intermediate hopper 14. On the bottomof the vacuum hopper 22, there can be a valve such as a flapper valve 43with a counter weight attached. While the vacuum of the vacuum hopper 22is energized this creates a seal between the flapper valve 43 and thebottom of the vacuum hopper 22. When the vacuum stops, the weight of thematerial that was picked up allows the flapper valve 43 to open and thematerial drops into the intermediate hopper 14. The intermediate hopper14 has a fitting on the bottom that extends into the top of a feedhopper 31 of the delivery apparatus 18. The feed hopper 31 includes apair of outlet ports 32, 34 (although one or more outlets may beprovided) which are each connected to a delivery tube 36, 40. The freeends of the delivery tubes 36, 40 terminate in feed heads 46 whichdeliver the flux to the mold 13 (or a plurality of molds). The feedheads 46 may form or comprise a distributor to spread the mold flux onthe mold surface. The mold flux is pneumatically fed from the feedhopper 31 with venturi pumps 41 which are operatively connected to theoutlet ports 32, 34. The number of ports or venturi pumps may varydepending on the type of continuous casting machine or shapes cast.

In one embodiment, the control apparatus 16 further includes a one ormore load cells 42 which support the intermediate hopper 14. The loadcells 42 can be used to determine the weight of the intermediate hopper14 and the mold flux contained therein. In one embodiment theintermediate hopper 14 can be isolated from the feed hopper 31 to avoidthe feed hopper 31 contributing to the measured weight. The weight ofthe intermediate hopper 14 can be monitored over a period of time so asto allow the consumption of flux to be monitored in real time.

As shown in FIG. 2, in one embodiment, the control apparatus 16 furtherincludes a controller 44, such as a programmable logic controller(PLC—which may be part of a SCADA (i.e., supervisory, control and dataacquisiton) system) or any other suitable computer processor. Thecontroller 44 receives inputs from the load cells 42 and/or otherprocess parameters relating to the metal casting process conditions, andcontrols the operation of the vacuum 22 in response. Specifically, thecontroller 44 causes the vacuum 22 to turn on, thus causing mold flux tofeed into the intermediate hopper 14, based on a predetermined weight ofthe feed hopper 31 as compared to the consumption or loss of weight ofmold flux calculated using the output of the load cells 42.

In one embodiment, the mold flux composition and rate at which the moldflux is delivered into the mold can be adjusted by the operator using anoperator control screen 48 on the controller 44 that can be used foradjusting the feed rate. Alternatively, the mold flux composition andrate at which the mold flux is delivered into the mold 13 can beadjusted by the operator by a wireless handset 50 in communication witha receiver 52 on controller 44. The wireless handset 50 can be used tocontrol the feed rate instead of the operator control screen 48.

Although only one silo 20 is shown in FIG. 1, a plurality of silos 20 a,20 b, 20 c can be provided, as shown in FIG. 3. Although FIG. 3 showsthree separate silos, it will be appreciated that any number of silosmay be provided. The silos may also be implemented as separate chambersin a single unit.

In one embodiment, each of the silos 20 a-c contain a different flux orflux component having a different composition. The silos 20 a-c are eachconnected to the suction tube 28 at a manifold via a valve 54 a-c. Thevalves 54 a-c are actuated via the controller 44 (or a separate,standalone controller). Accordingly, the valves 54 a-c can be controlledso as to selectively connect a chosen silo 20 a-c to the suction tube28.

In one embodiment, the receiver 52 (or a separate, standalone receiverwhich may be wired or wireless) of the controller 44 receives parametersregarding the casting process. In particular, the receiver 52 mayreceive real time measurements from sensors and/or operator enteredcharacteristics for the casting process. For example, the receiver mayreceive data including one or more of: the grade of metal being cast(e.g. the grade of steel), casting rate/speed, flux consumption rate(which can be measured using the load cells 42 as described above), heattransfer rate (determined by measuring a temperature increase of coolingwater used to cool the mold 13), and the temperature of the slag on topof the mold 13. In particular, Infrared (IR) sensors may be used tomeasure the surface temperature. Alternatively, thermocouples or othertemperature sensors may be used. A laser distance measurement device mayalso be used to determine the thickness of the layer of flux of themolten metal. The parameters may also include the metal temperature,thickness, width, section size, taper, etc.

In one embodiment, in response to the received parameters, thecontroller 44 determines the desired composition for the flux andselects the required silo 20 a-c by opening the valve 54 associated withthe selected silo 20 and closing the other valves 54. Alternatively, thecontroller 44 may supply flux which is a mixture of the fluxes or fluxcomponents from a plurality of the silos 20 a-c. The valves 54 a-c mayallow the relative proportions of each flux to be controlled to providethe desired flux composition. For example, the valves 54 a-c may bemetering valves which can accurately control the flow of flux. It willbe appreciated that the silos 20 a-c could instead contain constituentelements of mold flux (as opposed to flux itself) which can be combinedto provide the desired composition.

In one embodiment, the controller 44 may identify the required fluxcomposition using fuzzy logic, artificial neural networks or otherartificial intelligence functions. The controller 44 may determine thecorrect flux based on the real time process parameters. The fluxcomposition may be adjusted during the casting process or may be fixedfor a specific casting run. The controller 44 may determine the fluxcomposition and select the required silo(s) automatically using analgorithm. The controller 44 may determine whether a current fluxcomposition is appropriate (e.g. optimized) for the current processparameters and, if required, make adjustments to the flux or fluxcomponents delivered to the mold so as to provide the required fluxcomposition. The controller 44 need not carry out such adjustmentsautonomously and may instead generate an alert (e.g. an audible orvisible alarm) which signals to an operator that a change in fluxcomposition is desirable. If appropriate, the operator may instruct thecontroller to make such a change. The precise details regarding thecorrective action required may be generated automatically by thecontroller 44 (such that the operator need only approve the change) ormay be provided by the operator.

Although the silos 20 a-c have been described as being connected to thesuction tubes 28 via valves 54 a-c, it will be appreciated that otherarrangements may be used. In particular, the silos 20 a-c may beconnected to the tubes 28 using a single valve. Alternatively, each silo20 a-c may have a dedicated suction tube 28 such that no manifold isrequired. In fact, the tubes 28 may deliver the flux or flux componentfrom its respective silo 20 a-c directly to the mold 13 such that thereis no requirement for the flux or flux components to be mixed. As afurther alternative, a robotic arm or the like may transfer the suctiontube 28 between silos 20 a-c in response to instructions from thecontroller 44.

It will be appreciated that the automatic selection of flux compositionmay be implemented using alternative flux feeding apparatuses than thatdescribed above. In particular, the flux feeding apparatus need not havean intermediate hopper 14 nor load cells 42. The flux may also bedelivered to the feed heads 46 using alternative means to thevacuum-based system described.

In one embodiment, a method for delivering flux to a mold during acontinuous casting process is provided. In one embodiment, the methodincludes: receiving process parameters of the casting process at acontroller; analysing the process parameters using the controller;determining a required flux composition for the received processparameters; and connecting a feed head to one or more of a plurality ofsilos each containing a different flux or flux component so as todeliver flux of the required composition to the mold.

In another embodiment, the process parameter received by the flux feederconsists solely of the grade of metal to be cast. For example, the gradeof steel being cast in a continuous casting apparatus. As the steelgrade is changed (as an example), the plant control system and instructthe flux feeder system change the mold flux. The proper silo would openautomatically and the other silos would be closed, allowing the systemto vacuum the desired flux from the silo and apply it through thedistributor. In another embodiment, the flux feeder system can operateto run out the flux in the system before the next flux is selected.

In another embodiment, flux feeder can receive internal signals from thefeeder and from the metal casting process system. For example, the fluxfeeder can receive internal signals relating to the flux feed rate andprocess parameters, such as for example, heat removal rate from thecaster, which when combined are good indicators of flux performance andcan be adjusted in real time by mixing fluxes to establish and maintainan optimal balance. This embodiment would also involve metering out ofthe silos with inline mixing of the fluxes.

The invention is not limited to the embodiments described herein, andmay be modified or adapted without departing from the scope of thepresent invention.

For the avoidance of doubt, the present invention includes the subjectmatter as defined in the following numbered paragraphs (abbreviated“Para”):

Para 1. A flux feeding apparatus for delivering flux to a mold during acontinuous casting process, the apparatus comprising:

a feed head selectably connectable to a plurality of silos eachcontaining a different flux or flux component;

a receiver for receiving process parameters of the casting process; and

a controller which is configured to:

analyse the process parameters received by the receiver;

determine a required flux composition for the received processparameters; and

connect the feed head to one or more of the plurality of silos so as todeliver flux of the required composition to the mold.

Para 2. A flux feeding apparatus as described in Para 1, wherein theprocess parameters include user-input parameters and sensed parameters.

Para 3. A flux feeding apparatus as described in Para 1 or 2, whereinthe process parameters include one or more of: the metal being cast,casting rate/speed, flux consumption rate, heat transfer rate, and slagtemperature.

Para 4. A flux feeding apparatus as described in any preceding Para,wherein the controller connects the feed head to a plurality of thesilos so as to form a mixture of the individual fluxes or fluxcomponents.

Para 5. A flux feeding apparatus as described in any preceding Para,wherein the controller connects the feed head to one of the silos so asto deliver the flux contained therein to the mold.

Para 6. A flux feeding apparatus as described in any preceding Para,wherein the feed head is connected to the silos via a manifold and oneor more valves which selectively couple the silos to the feed head.

Para 7. A flux feeding apparatus as described in Para 6, wherein the oneor more valves are metering valves.

Para 8. A flux feeding apparatus as described in any preceding Para,further comprising one or more sensors for determining the processparameters, the one or more sensors being connected to the receiver.

Para 9. A flux feeding apparatus as described in any preceding Para,further comprising an intermediate hopper and a transfer apparatus fortransferring mold flux from the silos to the intermediate hopper,wherein the feed head is connected to a feed hopper which is configuredto receive flux from the intermediate hopper.

Para 10. A flux feeding apparatus as described in Para 9, wherein thetransfer apparatus includes a vacuum for transferring flux from thesilos to the intermediate hopper, and wherein the controller is furtherconfigured to control the operation of the vacuum.

Para 11. A flux feeding apparatus as described in Para 9 or 10, whereinthe transfer apparatus further comprises a valve which is operablebetween a first closed position which prevents mold flux fromtransferring to the intermediate hopper when the vacuum is on, and asecond open position which allows mold flux to transfer to theintermediate hopper when the vacuum is off.

Para 12. A flux feeding apparatus as described in Para 11, wherein thevalve is a flapper valve having a counter weight.

Para 13. A flux feeding apparatus as described in any preceding Para,further comprising a venturi pump to supply the flux to the feed head.

Para 14. A continuous casting apparatus comprising a flux feedingapparatus as described in any preceding Para.

Para 15. A method for delivering flux to a mold during a continuouscasting process, the method comprising:

receiving process parameters of the casting process at a controller;

analysing the process parameters using the controller;

determining a required flux composition for the received processparameters; and

connecting a feed head to one or more of a plurality of silos eachcontaining a different flux or flux component so as to deliver flux ofthe required composition to the mold.

1. A flux feeding apparatus for delivering flux to a mold during acontinuous casting process, the apparatus comprising: a plurality ofsilos each containing a different flux or flux component; a receiver forreceiving process parameters of the casting process; and a controllerwhich is configured to: analyse the process parameters received by thereceiver; determine whether a current flux composition is appropriatefor the received process parameters; and if the current flux compositionis not appropriate for the received process parameters, change thedelivery of flux or flux components from the plurality of silos toprovide a required flux composition to the mold for the received processparameters.
 2. A flux feeding apparatus as claimed in claim 1, whereinthe process parameters include user-input parameters and sensedparameters.
 3. A flux feeding apparatus as claimed in claim 1, whereinthe process parameters include one or more of: the grade of metal beingcast, casting rate/speed, flux consumption rate, heat transfer rate,slag temperature, metal temperature, thickness, width, section size,taper.
 4. A flux feeding apparatus as claimed in claim 1, wherein thecontroller selects a plurality of the silos so as to form a mixture ofthe individual fluxes or flux components.
 5. A flux feeding apparatus asclaimed in claim 1, wherein the controller selects one of the silos soas to deliver the flux contained therein to the mold.
 6. A flux feedingapparatus as claimed in claim 1, further comprising a feed head which isconnected or connectable to the plurality of silos, wherein thecontroller is configured to supply the feed head with flux or fluxcomponents from one or more of the plurality of silos so as to deliverthe required flux composition to the mold.
 7. A flux feeding apparatusas claimed in claim 6, wherein the feed head is connected to the silosvia a manifold and one or more valves which selectively couple the silosto the feed head.
 8. A flux feeding apparatus as claimed in claim 7,wherein the one or more valves are metering valves.
 9. A flux feedingapparatus as claimed in claim 6, wherein one or more mixing devices areprovided to mix the flux or flux components prior to or in the feedhead.
 10. A flux feeding apparatus as claimed in claim 6, furthercomprising an intermediate hopper and a transfer apparatus fortransferring mold flux from the silos to the intermediate hopper,wherein the feed head is connected to a feed hopper which is configuredto receive flux from the intermediate hopper.
 11. A flux feedingapparatus as claimed in claim 10, wherein the transfer apparatusincludes a vacuum for transferring flux from the silos to theintermediate hopper, and wherein the controller is further configured tocontrol the operation of the vacuum.
 12. A flux feeding apparatus asclaimed in claim 11, wherein the transfer apparatus further comprises avalve which is operable between a first closed position which preventsmold flux from transferring to the intermediate hopper when the vacuumis on, and a second open position which allows mold flux to transfer tothe intermediate hopper when the vacuum is off.
 13. A flux feedingapparatus as claimed in claim 12, wherein the valve is a flapper valvehaving a counter weight.
 14. A flux feeding apparatus as claimed inclaim 1, further comprising a venturi pump to supply the flux to thefeed head.
 15. A flux feeding apparatus as claimed in claim 1, wherein,if the current flux composition is not appropriate for the receivedprocess parameters, the controller generates an alert for an operator.16. A flux feeding apparatus as claimed in claim 15, wherein in responseto the alert, the operator instructs the controller to change thedelivery of flux or flux components from the plurality of silos toprovide a required flux composition to the mold for the received processparameters.
 17. A flux feeding apparatus as claimed in claim 1, furthercomprising one or more sensors for determining the process parameters,the one or more sensors being connected to the receiver.
 18. Acontinuous casting apparatus comprising a flux feeding apparatus asclaimed in claim
 1. 19. A method for delivering flux to a mold during acontinuous casting process, the method comprising: receiving processparameters of the casting process at a controller; analysing the processparameters using the controller; determining whether a current fluxcomposition delivered to the mold from a plurality of silos eachcontaining a different flux or flux component is appropriate for thereceived process parameters; and if the current flux composition is notappropriate for the received process parameters, changing the deliveryof flux or flux components from the plurality of silos so as to providea required flux composition to the mold for the received processparameters.